Wallbox dimmers are well known and frequently have a triac, a silicon controlled rectifier (SCR), a field effect transistor (FET), or any other controllably conductive semiconductor structure that is operable to deliver variable power to a lighting load. The controllably conductive device is frequently provided with an on/off control actuator and a dimmer level control actuator mounted in and operable from the front surface of the dimmer. It is desirable to also provide an air gap switch actuator, which can be located in and operated from the same front surface of the device to provide a definite disconnect of the alternating-current (AC) power from the lighting load, independent of the off-time of the controllably conductive power device.
It is very desirable to organize the control acutators on the front surface of the dimmer to present an attractive smooth and uncluttered appearance while also being easy to operate and being “self teaching” to the user.
A number of wallbox dimmers with such control acutators are well known.
One such device is sold by Lutron Electronics Co. Inc. under the trademark “MAESTRO” in which the faceplate of the wallbox dimmer has a relatively flat surface. A large rectangular on/off acutator occupies most of the faceplate surface for controlling the on and off operation of the semiconductor control device (or the controllably conductive device). A narrow vertically elongated area on one side of the tap switch contains a very narrow dimming control rocker actuator for controlling the dimming level of the connected lighting load by appropriate control of the semiconductor device. A further narrow area on the other side of the on/off actuator carries a line of spaced light emitting diodes (LEDs) or the like which illuminate in sequence to indicate the dimming level set by the dimming control rocker acutator.
Finally, an air gap switch actuator is contained below the on/off actuator. This air gap switch actuator is a thin, laterally movable control, moving along an axis of elongation from left to right to operate an internal air gap switch, which can positively disconnect the input AC power from the lighting load. Thus, the user need not rely on the semiconductor device to be nonconductive (through actuation of the on/off actuator) to insure that the lighting load is disconnected from the AC power (so that the load circuit can be more safely maintained). The air gap switch acutator moves an elongated shaft with an enlarged camming surface between two spring leafs which carry respective contacts located within the enclosure or housing of the dimmer. When moved to the open position, the cam shaft presses the leaf springs and thus their contacts apart to open the internal air gap switch.
The on/off actuator, the dimming control rocker actuator, and the air gap switch actuator are organized to present a flat surface in which the controls are approximately coplanar. (The actuators need very little motion from their planar surfaces to operate their respective switches within the dimmer enclosure and they protrude very little above the surface of the faceplate.) However, since the air gap switch actuator must move laterally between a left-hand position and a right-hand position, a gap necessarily exists to the left or to the right of the air gap switch actuator, depending on its setting. This is an unattractive gap in the otherwise continuous surface of the face. Further, the air gap switch actuator is hard to operate since its surface is flush with the adjacent faceplate surface; and it is difficult to clearly display to the user that the internal air gap switch is open, i.e., that no AC power is being delivered to the lighting load.
It would be very desirable to arrange the air gap switch of the “MAESTRO” dimmer so that it fills the surface of the face plate in a smooth, continuous manner and so that its off position is easily observable, and so that it is easily operated by a user.
Another wallbox dimmer made by Lutron Electronics Co. Ltd. is a device sold under the trademark “FAEDRA”. This device is unlike the “MAESTRO” device, but has an air gap switch actuator, which has a push/pull (or push/out) motion (as contrasted to the lateral motion of the “MAESTRO” dimmer). As in the “MAESTRO” dimmer, the push/pull control also moves an elongated cam-carrying shaft which cams apart a pair of leaf springs which carry respective contacts to open the contacts when the push/pull operator is moved to a position to open the internal air gap switch.
Such dimmers are shown in U.S. Pat. Nos. 6,734,381 and 6,727,446. This dimmer has a surface, which carries a vertically elongated elliptical contact for on/off actuation with a protruding relatively high elliptical surface, which occupies the major portion of the faceplate. A relatively high dimmer rocker actuator extends along one surface of the elliptical on/off actuator. The elliptical control button protrudes beyond the periphery of the dimmer rocker actuator, thus departing from a planar configuration for the faceplate. The push/pull air gap switch control then extends under the elliptical on/off actuator for the control of the semiconductor device.
To control the internal air gap switch, a groove is placed in the bottom surface of the air gap switch actuator, which can be operated by a user's finger or finger nail. It is not possible, however, to gain access to the air gap switch actuator from the top. Also, the operation or position of the air gap switch is not apparent to the user. Further, it is not part of a continuous smooth outer surface for the device face plate.